c++ - How to improve logic to check whether 4 boolean values match some cases

Question

I have four bool values:

bool bValue1;
bool bValue2;
bool bValue3;
bool bValue4;

The acceptable values are:

         Scenario 1 | Scenario 2 | Scenario 3
bValue1: true       | true       | true
bValue2: true       | true       | false
bValue3: true       | true       | false
bValue4: true       | false      | false

So, for example, this scenario is not acceptable:

bValue1: false
bValue2: true
bValue3: true
bValue4: true

At the moment I have come up with this if statement to detect bad scenarios:

if(((bValue4 && (!bValue3 || !bValue2 || !bValue1)) ||
   ((bValue3 && (!bValue2 || !bValue1)) ||
   (bValue2 && !bValue1) ||
   (!bValue1 && !bValue2 && !bValue3 && !bValue4))
{
    // There is some error
}

Can that statement logic be improved/simplified?

标签： c++if-statement

Answer 1

I would aim for readability: you have just 3 scenario, deal with them with 3 separate ifs:

bool valid = false;
if (bValue1 && bValue2 && bValue3 && bValue4)
    valid = true; //scenario 1
else if (bValue1 && bValue2 && bValue3 && !bValue4)
    valid = true; //scenario 2
else if (bValue1 && !bValue2 && !bValue3 && !bValue4)
    valid = true; //scenario 3

Easy to read and debug, IMHO. Also, you can assign a variable whichScenario while proceeding with the if.

With just 3 scenarios, I would not go with something such "if the first 3 values are true I can avoid check the forth value": it's going to make your code harder to read and maintain.

Not an elegant solution maybe surely, but in this case is ok: easy and readable.

If your logic gets more complicated, throw away that code and consider using something more to store different available scenarios (as Zladeck is suggesting).

I really love the first suggestion given in this answer: easy to read, not error prone, maintainable

(Almost) off topic:

I don't write lot of answers here at StackOverflow. It's really funny that the above accepted answer is by far the most appreciated answer in my history (never had more than 5-10 upvotes before I think) while actually is not what I usually think is the "right" way to do it.

But simplicity is often "the right way to do it", many people seems to think this and I should think it more than I do :)